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charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Nov 5, 2020 at 6:30 PM Catalin Marinas wrote: > > On Thu, Nov 05, 2020 at 12:18:47AM +0100, Andrey Konovalov wrote: > > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > > index 14b0c19a33e3..cc7e0f8707f7 100644 > > --- a/arch/arm64/kernel/mte.c > > +++ b/arch/arm64/kernel/mte.c > > @@ -23,6 +23,8 @@ > > #include > > #include > > > > +u64 gcr_kernel_excl __ro_after_init; > > + > > static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) > > { > > pte_t old_pte = READ_ONCE(*ptep); > > @@ -123,6 +125,23 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag) > > > > void __init mte_init_tags(u64 max_tag) > > { > > + static bool gcr_kernel_excl_initialized = false; > > + > > + if (!gcr_kernel_excl_initialized) { > > + /* > > + * The format of the tags in KASAN is 0xFF and in MTE is 0xF. > > + * This conversion extracts an MTE tag from a KASAN tag. > > + */ > > + u64 incl = GENMASK(FIELD_GET(MTE_TAG_MASK >> MTE_TAG_SHIFT, > > + max_tag), 0); > > + > > + gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK; > > + gcr_kernel_excl_initialized = true; > > + } > > + > > + /* Enable the kernel exclude mask for random tags generation. */ > > + write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1); > > Same question as on a previous patch. Is SYS_GCR_EL1 written on the > other registers via cpu_enable_mte()? You mean for other CPUs? mte_init_tags() is called for each CPU if that's what you mean. Otherwise, please clarify the question.